The present invention relates to one-component RTV compositions and processes and more particularly the present invention relates to low modulus alkoxy functional, one-component RTV compositions and processes.
The earliest type of one-component RTV compositions were ones in which a cross-linking agent was an acyloxy-functional silane as disclosed in Ceyzeriat, U.S. Pat. No. 3,133,891 and Bruner, U.S. Pat. No. 3,035,016. Further, the disclosure of Kulpa, U.S. Pat. No. 3,296,161, Goossens, U.S. Pat. No. 3,296,195 and Beers, U.S. Pat. No. 3,438,930, relate to the use of certain self-bonding additives to make such compositions self-bonding. While such acyloxy-functional compositions were fast-curing and had other desirable properties, nevertheless they have two disadvantages. One disadvantage is that they released acetic acid upon curing which was somewhat corrosive. Further, such acetic acid gave off an objectionable odor such that it was somewhat difficult to work with this system within an enclosed enivronment.
Accordingly, it early became highly desirable to have a non-corrosive, fast-curing, one-component RTV system. The two-component RTV systems as exemplified by Nitzsche et al., U.S. Pat. No. 3,127,363 were non-corrosive. However, such compositions had to be prepared in two packages and mixed immediately prior to application of the system and once they were mixed they had to be used in a short period of time, otherwise the composition would not cure at a sufficiently fast rate. Accordingly, even though such compositions were non-corrosive, nevertheless they require additional labor cost in the application of the system, and once mixed the system had a very poor shelf life.
An early example of such alkoxy-functional composition in the one-component form is to be found in Nitzsche et al., U.S. Pat. No. 3,065,194. However such composition suffered from the fact that there has to be utilized vigorous drying in the preparation of the composition, and that the composition also has a short shelf period. Other alkoxy-functional one-component RTV compositions are to be found in Brown et al., U.S. Pat. No. 3,122,522, and Brown et al., U.S. Pat. No. 3,161,614 or U.S. Pat. No. Re 29760. These compositions were not sufficiently fast-curing, that is, if they cured at all, they would cure at a very slow rate especially after they had been stored for some time, that is a period of a week or more. It was found that such compositions would not cure at a sufficiently fast rate with the normal condensation catalysts that were used in the acyloxy systems.
Accordingly, there was devised various titanium chelate catalysts for such alkoxy-functional, one-component RTV systems. Examples of titanium chelate catalysts in alkoxy one-component RTV systems are to be found in the disclosures of Weyenberg, U.S. Pat. No. 3,334,067, Cooper et al., U.S. Pat. No. 3,542,901 and Smith et al., U.S. Pat. Nos. 3,689,454 and 3,779,986--the last two being assigned to the same assignee as the present invention.
A further example of such systems which were commercialized in one form or another and particularly with various types of additives, are to be found in the disclosure of Beers, U.S. Pat. No. 4,100,129. All the patents referred to in this application are incorporated by reference. This latter patent discloses an alkoxy-functional, one-component RTV system as stated above, which is commercialized and particularly dependent upon a specific type of chelate catalysts to give the composition a sufficient curing rate after the composition had been stored for periods of time, 6 months or more. In the disclosure of U.S. Pat. No. 4,100,129 there is disclosed that alkoxy one-component RTV systems may have in particular a tri-functional containing polysiloxane fluid and a linear trimethylsiloxy dimethylpolysiloxane fluid and various types of adhesion promoters. It is disclosed in this disclosure that various types of adhesion promoters may be utilized with such alkoxy-functional, one-component RTV systems such as silyl isocyanurates and other compounds. However, as stated previously, such compositions still suffer from the fact that they are not sufficiently shelf stable and they are not sufficiently fast-curing.
Another example of a somewhat non-corrosive, one-component RTV system is, for instance, to be found in the disclosure of Beers, U.S. Pat. No. 4,257,932. This patent discloses an acyloxy-functional, one-component RTV system wherein the acyloxy-functional cross-linking agent is preferably methyltris-2-ethylhexanoxysilane. It is disclosed that various additives may be utilized in such systems such as for instance a fluid polysiloxane having a high degree of tri- or tetrafunctionality, a similar fluid as was disclosed in U.S. Pat. No. 4,100,129 as well as a dimethylpolysiloxane fluid. In addition there is disclosed the presence of various additives such as adhesion promoters and other additives. While the system of U.S. Pat. No. 4,257,932 was somewhat non-corrosive, nevertheless since it released an acid, albeit one of high molecular weight, it still was corrosive and still was not as fast-curing as would be desired. Further, in particular, it should be noted its nature of corrosion was such that it would cause discoloration of various substrates and even be somewhat hard to bond to substrates with various types of self-bonding additives. Examples of several self-bonding additives that could be utilized with such a composition is as for instance disclosed in the foregoing U.S. Pat. No. 4,257,932, as well as Mitchell, et al., U.S. Pat. No. 4,273,698 which disclosed the use of various silyl fumarates, silyl maleates, silyl succinates and other compounds as adhesion promoters for such compositions as well as for alkoxy-functional, one-component RTV systems. Another disclosure that deals with the utilization of large amounts of calcium carbonate as a filler in such compositions so as to make them paintable is in Smith et al., U.S. Pat. No. 4,247,445. Another disclosure in this area is Dziark, et al., U.S. Pat. No. 4,308,372. which relates to the prereacted reaction product of the adhesion promoter and the cross-linking agent so as to impart further shelf stability to the system. However, even with such prereacted systems of cross-linking agent and adhesion promoter, such systems still suffer from shelf stability problems. Another disclosure which is pertinent is Wright et al., U.S. Pat. No. 4,261,758 which deals with the use of polyethers as sag control agents or as agents to make the composition thixotropic by the incorporation in the composition of small amounts of polyethers.
Recently, there has been devised a stable substantially acid-free, one-package moisture curable polyalkoxy-terminated organopolysiloxane system having as a condensation catalyst, preferably a tin compound as disclosed in White et al., U.S. Pat. No. 4,395,526 and Halgren, U.S. Pat. No. 4,377,706. Another relevant patent application in this area is Chung, U.S. Pat. No. 4,424,157 which deals with the utilization of a particular scavenger in such systems, and Lucas et al., Docket 60Si-585, Ser. No. 349,538, now U.S. Pat. No. 4,483,973, which was filed on the same date as the present case which deals with the utilization of various types of adhesion promoters in such systems and in the preferred system of the instant case. There is also the patent of Dziark, U.S. Pat. No. 4,417,042 which concerns the use of certain silazanes and silyl-nitrogen polymers as scavengers with a polyalkoxy base organopolysiloxane polymer. These are some of the scavenging systems not in the White et al. patent, U.S. Pat. No. 4,395,526. The Dziark patent, U.S. Pat. No. 4,417,042 was filed on the same date as the present case. The scavengers and RTV system of U.S. Pat. No. 4,417,042 is preferably cured with the additives of the present case although it should be understood that the additives of the present case can be used with any of the RTV systems of White et al., U.S. Pat. No. 4,395,526. Substantially, the utilization of certain scavengers in alkoxy-functional, one-component RTV systems so as to remove or tie up most hydroxy groups in the uncured polymer compositions, results in the composition having good shelf stability and a good cure rate even with a tin soap catalyst. Further, the system is non-corrosive.
It was also desirable to make such compositions low modulus, that is that such compositions have a low tensile strength and high elasticity so that they could be utilized in glazing and sealant applications especially in high-rise construction work. It was also desirable to make such composition self-bonding as was disclosed in the foregoing Lucas et al., Ser. No. 349,538 now U.S. Pat. No. 4,483,973. There has been a continuing search for additional self-bonding additives and there has been an attempt to make such compositions as low-modulus as possible which was not the case with the basic system disclosed in White et al., U.S. Pat. No. 4,395,526, which was disclosed above.
Accordingly, it is one subject of the present invention to provide for one-component, alkoxy-functional RTV systems, which is self-bonding by the use of novel self-bonding additives.
It is an additional object of the present invention to provide for an alkoxy-functional, one-component RTV system which is low modulus, that is, has a low tensile strength and a very high elongation.
It is still an additional object of the present invention to make one-component RTV systems which are substantially noncorrosive, shelf stable, and which have a low modulus.
It is still a further object of the present invention to make a low cost one-component RTV composition that is low modulus by incorporating various ingredients into the composition.
It is still further an additional object of the present invention to provide a process for producing a one-component RTV system which is non-corrosive, low modulus, low cost and is shelf stable.
These and other objects of the present invention are accomplished by means of the disclosures set forth herein below.